一道看有疑惑的题，请帮忙解答GWD-18-2

According to findings derived from functional magnetic resonance imaging (MRI), the area of the brain in which a second or third language is stored depends on the age of the language learner; whereas each language occupies a distinct area of the brain in an adult learner, language areas overlap in a young child.

1. whereas each language occupies a distinct area of the brain in an adult learner,
2. whereas for adults each language occupies a distinct area of the brain and
3. each language occupies a distinct area of the brain when they are learned by an adult, while
4. each language in adults occupied a distinct area of the brain, while
5. each language occupying a distinct area of the brain for an adult learner, and

为什么选a？选a的话。红色不分做什么成分？

请楼主在标题里面给出题目出处，方便大家回帖，方便后人查询，谢谢啊

另外，多个题目，恳请一题一贴，才能方便讨论！

各个区的发贴规范：

GMAT语法区版规
http://forum.chasedream.com/dispbbs.asp?boardID=23&ID=79830

方便自己，方便他人，感谢您的理解和支持！

PS: 点击帖子右下脚 可以修改您的帖子，编辑标题

1. whereas each language occupies a distinct area of the brain in an adult learner,
     
2. whereas for adults each language occupies a distinct area of the brain and
      
3. each language occupies a distinct area of the brain when they are learned by an adult, while
     
4. each language in adults occupied a distinct area of the brain, while
     
5. each language occupying a distinct area of the brain for an adult learner, and

黄色部分为错误，D应该没有语法错误，只是稍微改变了原意

language areas overlap in a young child，就是后半句的主句啊

B 的 and 为什么错了，我觉得应该选B 因为它有两个连词，不应该选A，因为只有一个连词。

期待解答....